Researchers looked at the chemicals’ effect on the success of in vitro fertilization, or IVF, in which an egg is removed from a woman’s uterus, grown to an embryo in a petri dish, then implanted back into the uterus.

In one study, Lindsey Konkel reports, women with higher concentrations of bisphenol A, or BPA, had lower peak levels of estradiol, a form of estrogen that helps eggs develop. In another, researchers found a link between blood concentrations of polychlorinated biphenyls (PCBs) and the rate at which embryos attached to the uterine wall. Finally, in a third study, women with the highest hexachlorobenzene (HCB) levels in their blood were more likely to experience a failed embryo implantation than those with the lowest levels.

The interesting, and rather alarming, thing here is that two of the chemicals have been banned in the United States for years. HCB, a pesticide, has been banned here since1984, though it is still used in some other countries and may be created as an impurity in the making of other pesticides and chemicals. PCBs, a class of industrial fluids used mostly in electrical equipment, have been banned since 1979, but their persistence in the environment means they still show up in the blood of more than 95 percent of Americans older than 12.

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Environmental Health News points out that “causes of infertility are numerous, ranging from hormonal imbalances, to defects of the uterus, to misshapen sperm, low sperm count or low sperm motility in men.” But these new findings are worth considering given what we’ve learned in recent years:

Some scientists now theorize that endocrine-disrupting chemicals in the environment also can reduce fertility. Endocrine disruptors are a class of more than 1,200 chemicals that can mimic or block hormones, including estrogen, the primary female sex hormone involved in pregnancy.

“These chemicals may affect the way hormones regulate many aspects of our bodies, potentially even the ability to get pregnant,” said Laura Vandenberg, a reproductive scientist at Tufts University.

It’s unclear yet whether these findings are unique to the IVF community, or if we are just seeing the tip of the iceberg of a problem that extends beyond this population,” said Tracey Woodruff, a reproductive health scientist in the division of Maternal-Fetal Medicine at the University of California, San Francisco Medical Center who was not involved in the studies.

There’s not much any of us can do to limit exposure to PCBs or HCB; they’re basically everywhere. But it’s clear that avoiding BPA as much as possible is still good policy for any woman who may one day bear children—and, in my view, for those of us who will never bear children as well. If it’s toxic enough to torpedo a pregnancy, I certainly don’t want it in my blood, either. See the Environmental Working Group’s tips on the best ways to avoid BPA in your life.